Crankshaft forging apparatus



3 Sheets-Sheet l E. VOM BOVERT CRANKSHAF'T FORGING APPARATUS Nov. 10,1959 Filed Jan. 2e, 1954 Fig] /NvENToR mmf/BM sy.- MMM/Mw HTTORNE Nov.10, 1959 E. Vom BovERT A l2,911,705

CRANKSHAFT FORGING APPARATUS 3 Sheets-Shee'cl 2 Filed Jan. 26, 1954INVENTOR wwmmwow/LZ' Nov. 10, 1959 E. voM'BovERT 2,911,705

CRANKSHAFT FORGING APPARATUS Filed Jan. 26, 1954 ssheets-sheet 5 Fig. 6Y 22 Pfg. 7

mullll-m- HTTORNEE/ United States Patent CRANKSHAFT FORGING APPARATUSErnst vom Bovert, Augsburg, Germany Application January 26, 1954, SerialNo. 406,233

Claims priority, application Germany January 27, 1953 3 Claims. (Cl.29-6) The present invention relates to -forging apparatus, and moreparticularly to crankshaft forging apparatus for forging crankshafts ofthe type which are used in internal combustion engines.

The art of forging crankshafts of the above type is already welldeveloped, and it is possible for known forges to turn out goodcrankshafts in a relatively short period of time. However, the knownforging processes and apparatus can be greatly improved. In the firstplace, the forging dies are quite expensive, and companies whichmanufacture these crankshafts change their forging dies only after along period of time because of the great expense involved. Furthermore,great amounts of heat are absorbed at a fairly fast rate from thework-pieces so that it is necessary with the known forging processes tointerrupt the production of the crankshafts for a relatively long periodof time in order to reheat the workpieces.

One of the objects of the present invention is to overcome the abovedrawbacks by providing a forging apparatus which involves forging eachcrankshaft in a plurality of stages which do not require interruption ofthe forging apparatus during each stage thereof.

Another object of the present invention is to provide a forgingapparatus which is capable offorging the entire crankshaft, except `forthe journals thereof, in two stages which place the crankshaft in acondition which requires machining of only the crank pins and journals.

An additional object of the present invention is to provide a forgingapparatus which is capable of quickly performing the yforging operationsso that there is not sufficient time for the work-pieces to cool enoughto require interruption of the forging operations for reheating of thework-pieces. n y

A further object of the present invention is to provide a forgingapparatus with forging dies which 'absorb a very small amount of heatfrom the work-pieces so that the necessity for interrupting the forgingoperations for reheating the work-pieces is eliminated in this way also.

VStillanother object of the present invention is to provide a forgingapparatus which is capable of being used with many different dies sothat the same apparatus can be used for a number of different forgingoperations.

A still further object of the present invention is to provide forgingdies which prevent the formation of flash on the work-pieces.

Yet another object of the present invention is to provide forging dieswhich are capable of cooperating with a wedge member insel-table intothe dies for giving the work-pieces the desired shape.

. Also, it is an object of the present invention to provide a forgingprocess and apparatus which is capable of automatically forming acounterweight on each web of a crankshaft.

' With the above objects in view, the present invention mainly consistsof an apparatus for forging crankshafts and including the apparatus forrough-forging portions of the crankshaft located between the journalsthereof firice into substantially U-shaped portions each of which has acrank pin section spaced from and connected at its ends to a pair ofsuccessive journals of the crankshaft by a pair of webs, locating eachof the U-shaped portions in a finish-forging position 90 displaced fromits roughforging position, and applying to each pair of webs in thefinish-forging position thereof a finish-forging force eX- tendinglaterally across the pair of webs to decrease the width thereof.

Also, with the above objects in view, the present invention mainlyconsists of a forging apparatus 'which includes a stationary support, amovable support located opposite the stationary support and beingcarried thereby for movement toward and away from the stationarysupport, and a plurality of rst die carriers fixed to the stationarysupport and facing the movable support. A plurality of second diecarriers are fixed to the movable support, face the stationary support,and are respectively located opposite the rst die carriers. A pluralityof die members are removably mounted on the rst and second die fcarriers, respectively, so that the die members may be interchanged withother die members to carry out different -forging operatlons with thesame supports and carriers.

The novel features which are considered as charac-` teristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe.

best understood from the following description of specic embodimentswhen read in connection with the accompanying drawings, in which:

Fig. 1 is a fragmentary partly sectional elevational view taken alongline I-I of Fig. 2 in the direction of the arrows; Y

j Fig. 2 is plan view of the structure of Fig. 1 and is taken along lineII-II of Fig. l in the Vdirection of the arrows, the parts locatedaboveand connected to the structure located above section `line II--II ofFig. lv

being omitted from Fig. 2;

Fig. 3 is a fragmentary, sectional, elevational viewf the presentinvention;

Fig. 7 is a view of the crankshaft of Fig. 6 as seen from the left endthereof;

Fig. 8 is a fragmentary view of the blank of Fig. 6 after it has beenformed with journals;

, Fig. 9 is a sectional view taken along line IX-IX of. Fig. 8 in thedirection of the arrows;

Fig.10 is a fragmentary View of the crankshaft blank after it has beenformed with crank portions;

Fig. 11 is a sectional view taken along'line XI-XI of` Fig. l0 is thedirection of the arrows;

Fig. 12 is a fragmentary elevational view of the crankshaft after theLprocess of the invention is completed;

Fig. 13 is a sectional View taken along line XIII-XIII of Fig. 12 in thedirection of the arrows;

Figf 14 is a top plan View of the crankshaft portion 1 shown in Fig. 13;and

Fig. 15 is a sectional View similar to Fig. 13 of a slight- 5 lymodified crankshaft.

Referring now to the drawings, the crankshaft fom-tedV by the processand apparatus of the invention is shown 'f in various stages in Figs.6-15. Figs. 6 and 7 show the setas-'to' be provided with the journals 30shown in Figs.. 8i and 9. Thereafter, the blankpor-tions 33 located'. between the journalsA 30 are forged one after-the other intothe.crankshaft portions 31 shown-in Fig.. l0, these crankshaft? portions 31beingformedV by a stationary forging dieland almovable forging die whichmoves'.4 downwardly in thedirection of arrow 32S of- Fig. 11 againsttheV successivefportions 33 of the blank.

It should be noted that the crankshaft blank is turned through.- a;predetermined? angle about itsaxis between forging of' the successivecrankshaft portions 312 so that the: successive crankshaft portions 31-are displaced'with respect. to: each other through desired angulardistances. For: example, depending on theV type of crankshaft,- theportions 31'` thereof will-be displaced by 90, 120 or 180 with'y respectto each-other.

is' apparent fromE Fig. ll,- the" crankshaft, when in the stage"A ofmanufacture shown-in-Fig. l0, is provided at. each: of its crankshaftportions 31 with acrank pin section 35i` having thesubstantiallyelliptical shape shown intl-lig;Y 1l and with a pair ofwebs 34 connectingthe ends ofthe crankshaftsection 35to-a-pairofsuccessive journals 3);V respectively. rlhe webs are wider inthe` stageof manufacture show n in Figs. l and l1 than in the finaliconiguration-shown-in- Fig. 13.- Fig. l2 shows the crank-- shaft in itsfinish-forged condition, and Fig. 14 shows oneof: the-'crank portions ofthe finish-forged crankshaft.

It will be noted that this last forging operation produces on the endsof the webs distant from the crank pin sections elongationsI 38 whichmay conveniently function as counter-weights. Fig. shows acrankshaftwhose blank is worked on by special forging dies to provide the"`crankshaft with the counterweight 39 during the forging of thecrankshaft. The crankshaft shown inFigs. 14- and- 15 need only bemachined at its` crank pin. and journal portions.

One possible apparatus constructed in accordance with the presentiinvention for carrying out a process which forges crankshafts in themanner described above in con-- nection with Figs; 6-15 is shown inFigs. 1-5. As may ber-seen' from Fig. l, the machine includes a base1b-of a forging press which is provided with a stationary sup-v portV 1inf the form of a plate which carries the saddleshaped die-carryingmembers 2 and 3,- the latter being removably fixed to the plate 1 bymoving them ontol the plate 1 in the direction of wedges 2d and intowedging engagement therewith; Thus, the apparatusincludes a pair ofouter, lower die carriers 2` and a pair of inner, lower die carriers 3.The inner, lowerv die carriers 3 are interconnected by a lowercrank-forming' die'4I located between-the carriers 3.

The apparatus of the invention includes a pair of upper movable supports5 and 6 which are interconnected by fairly heavy` straps 7 (Figs. 2 and3). The movable' supports 5 and 6` adjustably'carry upper die carriersSWhich are respectively arranged opposite the die carriers` 2 and' 3EAlso the' movable supports 5 and 6 areconnectedby heavy pull rods 9 tounillustrated pistons located irr unillustratedV cylinders arrangedbeneath the plate I in the v base 1b so that the movable supports 5 and6 may be moved with sui'cient force toward' (and away) from the plate fby applying hydraulic pressure' to these pistons.

4. Thus, it is possible to apply a force in the direction of arrows 9aof Fig. 3 to the upper movable supports 5 and 6 and the parts carriedthereby.

An upper movable press beam 10 is located over the supports 5 and 6 andis adapted to be moved down through a pressure cylinder and piston (notshown) in the direction of arrow 16a, and thento be moved up again. Thisbeam 10 carriers a die' carrier 11 which in turn removablycarries. therough-forgingl crank-formingy die 12 (Figs. l and 3) and thefinish-forging crank-forming die 13 (Fig. 4)- which isadaptedtocooperate with-a wedge member 14 (Figs. 4 andv 5), as will bedescribed below.

The upper and lower saddle-shaped die carriers 8, 2 and- 3-removablycarry throughthe medium of tongues and grooves 8b, 2b, and 3b,respectively, the dies 8a, 2a, and 3a, respectively. I'n the position ofthe parts shown in Fig. 1, which is the lowermost position of the upper,movable dies, tongues 2c and 3c of the lower dies matingly extend intogrooves of the upper dies to guarantee proper alignment between thesedies. The saddleshaped' die carrying members take up axial forces of thecrankshaft during the forging thereof to prevent axially elongationorcontraction of the crankshaft. When the apparatus is used for forginglarge crankshafts, the die carriers can each be made of two partsconnected together by space or studs, or the like. The dies 2a, 3a and8a serve to rough forge the journals 3i) of the crankshaft (Fig. 8).Finish-forging of these journals can be carried out with finishing dieswhich replace the rough-forging dies andv which give the journals thecylindrical shape shownin Fig. 9. Strips 19 are mounted on the plate 1,as shown in Fig..3, to take up forces which tend to move the diesforwardly'or rearwardly. Guide tubes 20 (Figs. 3 and 4)' guide thereciprocating movements of the pull rods 9A and are insulatedl againstheat.

The crankshaft blank 22, shown in Figs. 6 and 7, is prepared for theprocess of the invention by being turned slightly in a lathe in order toremove small flaws at the outer surface of the blank, this blank beingformed by the. process and apparatus of the invention into a crankshaftwhich, except for the crank pins and journals, need not be furthermachined. In order to forge crankshafts which at the end of the forgingoperation are to be machined at all parts thereof, it is sufficient tosimply forge the rough blank and clean the same by hand.

After heating of the blank 22, it is placed between the dies 2a, 3a, onthe one hand, and 8a, on the other hand, which are operated to form thejournals 30 shown in Fig. 8, the crankshaft being shifted along itslength after the operation of the dies so that the journals aresuccessively formed in pairs or in groups of four along the length ofthe crankshaft. For example, referring to Fig. l and assuming that thecrankshaft is advanced to the left', the'` right pair of dies 8a and 2aand 3a may roughly forge the journals and after theA crankshaft isadvanced to the-left the left set of dies 2a, 3a and 8a may finish forgethe journals to their cylindrical shape, so that the journals are formedin two stages by the dies shown in Fig. 1 as the crankshaft is advancedto the left, and one pair of journals is formed directly after apreceding pair. However, it is also possible to rough forge the journalsin groups of four with all of the dies shown in Fig. l, and then all ofthese dies may be replaced by finishforging` dies which give thejournals their final cylindrical shape, and in this latter event thejournals are finishforged in. groups of four. The choice as to one orthe otherof these processes will depend on such factors as the. size ofthe crankshafts.

All of the journals are forged on an entire group of crankshaft blankssuccessively. For example, in a given,

plant the first hours of the working day may be spent in forgingjournals on a number of crankshaft blanks which can be. completed in oneworking day. After thejournals are forged, the crankshaft blanks are:again reheated. and during this. time the right hand setof dies of Fig.l `are exchanged for dies corresponding to those on the left hand sideof Fig. 1 in the case where roughforging dies are located on the righthand side of Fig. l and finish-forging dies are located on the left handside of Fig. l. If all of the dies of Fig. l are rough-forging dies,then it is necessary to change all the dies to finishforging dies.

Now the step of the process which forms the crank portions 31 (Fig. 10)is carried out. A crankshaft blank with partly or fully forged journals30 is set up between the dies 2a, 3a, on the one hand, and 8a on theother hand. The supports 5 and 6 are then pulled down by the rods 9 sothat the blank is firmly held at the journals 30 by the dies shown inFig. l. Where finish-forging of the journals takes place in groups offour, this nishforging takes place at this time when the top dies ofFig. 1 are brought down against the blank. With the blank held in thismanner by the dies 2a, 3a, and 8a of Fig. 1, the beam 10 is lowered sothat the dies 12 engages the blank and cooperates with the die 4 to forma crank portion 31 on the blank (Figs. l, 3 and 10). Then the die 12 israised together with the dies 8a, and the blank is shifted axiallythrough a space equal to one crank portion and turned through thedesired angle of displacement between the successive crank portions, andthen the above operations are repeated to forge the next crank portion,and in this way the successive crank portions are formed. As is wellknown, a graduated template or the like is used in a known way forturning the crankshaft through the desired angle after the forging ofone crank portion `and before the forging of the next crank portion. Theprocessing of each of the crank shafts in this manner requires a veryshort time so that reheating of the crank shafts and undesirableinterrupting of the operations is avoided.

When these operations are complete, the die 12 is removed from thecarrier 11 and replaced by the die 13 and the die 4 is removed from theplate 1 and replaced by the die 15. The dies 2a, 3a and 8a functionduring the nish-forging step in the same way as they do in therough-forging step to hold the crankshaft at its journals and preventaxial elongation or contraction of the crankshaft during the forgingthereof.. For this finish-forging operation, each pair of webs of acrank portion are placed in a position which is 90 displaced from theirroughforging position. Thus, instead of extending vertically as they didat the end of the rough-forging operation, the webs of each crankshaftportion extend horizontally during the finish-forging operation.

The journals are again clamped in 'the dies 2a, 3a and 8a and each crankportion is placed successively in the die 15. Each pair of webs extendshorizontally across the upper central portion of die as indicated indotdash lines in Fig. 4. A wedge member 14 is placed between each pairof Webs and has a width corresponding to the space between the pair ofwebs. It will be seen from Fig. 15 that the lower left upwardly inclinededge portion of Wedge member 14 cooperates with a correspond-Y inglyshaped surface of die 15, while the upper left oppositely inclined edgeportion of member 14 cooperates with the die 13. The beam 10 is nowlowered and the die 13 moves downwardly to the position shown in Fig. 4so that the wedge member 14 is placed in the position shown in Fig. 4where it presses against the crank pin section of the crank portionlocated between dies 13 and 15 and where it prevents flash from formingon the webs. When the die 13 is raised the wedge member 14 remainsbetween the webs of the just-forged crank portion and a new member 14 isplaced between the webs of the succeeding crank portion. Thus, a newwedge member 14 is provided for each succeeding crank portion of thecrankshaft.

It is pointed out that in Fig. 4 the dot-dash line representation of therough-forged crankshaft portion is shown symmetrically with the outlineof the finish-forged crank 6 Y portion for the sake of bettercomparison. Actually, before the die 13 comes down into contact withwedge member 14 and the crankshaft, the latter is slightly higher thanthe dot-dash line position shown in Fig. 4 and rests on the bottom ofthe recess in the die 15, the wedge member 14 also being higher at thistime than the position thereof shown in Fig. 4. Upon engaging the wedgemember 14, the die 13 as it approaches the die 15 centers this Vwedgemember and moves it to the position shown in Fig. 4, and the webs andcrank pin of the crankshaft portion are changed to the outline shown insolid lines in Fig. 13.

A projection 41 of die 13 extends into a groove 42 of die 15, as shownin Fig. 4, and is located close to the space where the work piece islocated so as to prevent the formation of flash. In order to guaranteeuniformity in the sizes of the webs, even with variations in theoriginal dimensions of the blank, and in order to prevent undesirableupsetting of the material in the dies 13 and 15, the latter die isprovided with a free space 15a (Fig.

' 5) which does not conform to the shape and size of the final forgedwebs and which cooperates with a similar space in die 13 to provide achamber in which the end portions of each web distant from the crank pinend thereof may freely ow, so that this chamber thus serves to take upexcess material.

This material is available for balancing the crankshaft where the latteris of the type which is to be machined only at the crank pin and journalsectionsA thereof. However, if desired, this excess materialmay easilybe machined off. If the space 15a is made large enough and the dies 13and 15 properly shaped, it is possible to provide counterweights 39 onthe webs, as shown in Fig. 15, simultaneously with the finish-forgingoperation, the blanks being somewhat larger for this purpose.

As was mentioned above, each of the crank portions are successivelyfinish-forged in the above-described manner. The finish-forging part ofthe apparatus of the invention operates simply to quickly shape thesuccessive crank portions of each crankshaft so that the crankshaftsneed only be heated once.

With the apparatus of the invention a very superior crankshaft isproduced both with respect to the molecular structure of the metal andwith respect to the other properties thereof because after therough-forging operation, the material is yturned through and forgedagain in the finish-forging part of the apparatus. The apparatus of theinvention may be used with the smallest as Well as the largest blanks tomake crankshafts of faultless quality very economically and with thehighest accuracy. The apparatus of the invention can be built into andused with all conventional forging presses.

It will be understood that each of the elements described above, or twoor more together, may also iind a useful application in other types offorging apparatus differing from the types described above.

While the invention has been illustrated and described as embodied incrankshaft forging apparatus, it is not intended to be limited to thedetails shown, since various modications and structural changes may bemade without departing in any way from the spirit of the presentinvention.

Without further analysis, the foregoing will so full-y reveal the gistof the present invention thaty others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. Forging apparatus, comprising, in combination, a stationary support;a pair of movable supports located opposite said stationary support andbeing carried thereby for movement to-ward and away from said stationarysupport; al plurality of first die carriers fixed to said stationarysupport and facing said movable supports; a plurality of second diecarriers fixed to said movable supports, facing said stationary support,and being respectively located opposite said first carriers; a pluralityof die members removably mounted on said first and ment toward and awayfrom the latter; and a second' crank-forming die located between saidpair of movable supports and carried by said third support at the endthereof nearest said rst crank-forming die to cooperate with the latter,said crank-forming dies having end` surfaces which contact each other atthe end of the forging operation and which are located about the spacein said dies where the work-piece is located, one of saidA crankformingdies being formed adjacent said space with a groove and the other ofsaid crank-forming dies having a projection extending into said grooveWhen said end surfaces contact each other so as to preventthe formationof fiash on the work-piece.

2. Forging apparatus, comprising, in combination, a stationary support;a pair of movable supports located opposite said stationary support andbeing carriedthereby for movement toward and away from said stationarysupport; a plurality of first die carriers fixed to said stationarysupport and facing said movable supports;l a plurality of second diecarriers fixed to said movable supports, facing said stationary support,and' being respectively located opposite said first carriers; aplurality of die members removably mounted on said first and secondcarriers, respectively, so that said die members may be interchangedwith other die members to carry out different forging operations ywiththe same supports and carriers; a first crank-forming die mounted onsaid stationary support between a pair of said first die carriers andopposite the space between said pair of movable supports; a thirdmovable support mounted on. the apparatus opposite said first`crank-forming4 die for movement toward and away from the latter; asecond crankforming die located between said pair of movable supportsand carried by said third support at the end thereofv nearest said firstcrank-forming die to cooperatewith thelatter, said crank-forming dieshaving end surfaces whichV contact each other at the end of the forgingoperation and which are located about the space in said dies Where thework-piece is located; and a wedge member adapted to be located in saidspace to cooperate with` said' dies for giving the work-piece a desiredshape.

3. Forging apparatus comprising, in combination,`

means mounted on the apparatus for holding a Work-piece;

a stationary support; a first crank-forming die mounted` on saidstationary support and being formed with two pockets extending spacedfrom each other on opposite` sides of a vertical plane of symmetrythrough said first.

crank-forming die and substantially normal to said stationary support; amovable support mounted on the apparatus opposite said firstcrank-forming die for movement toward and away from the latter; a secondcrankforming dievcarried by said movable support at the end` thereofnearest said first crank-forming die to cooperate,

with the latter, said second crank-forming die having a pair of prongsextending spaced from each other from an end face of said secondcrank-forming die toward said first crank-forming die opposite saidpockets formed in the latter, said crank-forming dies having workingfaces respectively located between said pockets and said ,prongs andadapted to forge part of a crank, said prongs of said secondcrank-forming die entering said pockets during movement of said movablesupport toward said firstcrank-forming die before said working face ofsaid' second crank-forming die contacts the work-piece.

References Cited in the file of this patent UNITED STATES PATENTS356,974 Bagaley Feb. 1, 1887 1,403,696 Larcher Ian. 17, 1922 1,464,434Ljungstrom Aug. 7, 1923 1,717,513 Larcher June 18, 1929 2,064,323Schmidt et al. Dec. 15, 1936 2,080,640 Templin May 18, 1937 2,534,613Meley Dec. 19, 1950 2,653,373 Brauchler Sept. 29, 1953 2,694,952Clevenger Nov. 23, 1954 2,743,500 Berg May 1, 1956

